Process for treating hydrocarbon oils



LE ROY G. STORY Filed July 22, 1932 INVENTOR PROCESS FOR TREATINGHYDROCARBON OILS Aug. 11, 1936.

ATTORNEY Patented Aug. 11 I936 Le Roy G. Story, Beacon, N. Y., assignorto The Texas Company, New York, N. Y., a corporation of DelawareApplication my 22, 1932, Serial No. 623,990

2 Claims.

This invention relates to processes for the treatment of hydrocarbonoils and more particularly to processes forthe productionof gasoline ofhigh anti-knock value. 7

In accordance with my invention natural gasoline or other motor fuelhaving a relatively low anti-knock rating is reformed or converted toproduce gasoline of higher anti-knock value by the application of heatand pressure. The contained heat of the resulting reformed product isutilized in stripping straight-run gasoline from crude oil, thestraight-run gasoline thereafter being combined with the naturalgasoline or other product of low anti-knock value undergoingreformation. By utilizing a process embodying these steps production ofhigh antiknock gasoline may be economically carried out.

My invention will be more fully explained in the following descriptiontaken in conjunction with the accompanying drawing.

The single figure of the drawing is a diagrammatic view of an oiltreating system embodying my invention.

Referring more particularly to the drawing, natural gasoline or otherhydrocarbon motor fuel of low anti-knock value is introduced through acharging line I having a valve 2, into heating coil 3 of furnace 4. Theheated oil from the coil 3 travels through line 5, heat exchanger 6, andreducing valve 7 into fractionator 8.

In the fractionator 8 the products are sepa rated into vapors which passoff through line 9 and condenser into receiving drum H, and liquidproducts which are withdrawn from the fractionator through line l2having valve GI and are injected into flash chamber or separator l3through line l4 under pressure generated by pump l5. This pump may beeliminated where the pressure in fractionator 8 is great enough to forcethe condensate into line [4. Line l4 has a reducing valve I6 thereinwhich serves to lower the pressure on the liquid products, whichevaporate in the still l3. The flash chamber has baflle plates l1therein which serve to separate entrained particles from the vapors,which are carried through vapor line l8 into a second fractionator l9from which the lighter products pass off as vapors through line andcondenser 2| into receiving drum 22. Fractionator l9 has a trap-outplate or other means (not shown) for separating a side stream of naphthasuitable for reformation and this product may be conducted from thefractionator through return line 23 and pump 24 to line I, which leadsto the reformation coil 3. The line 23 has a valve 25 for controllingthe flow of side stream liquid from fractionator l9, and a connection 26is furnished for conducting final naphtha distillate from receiving drum22 into line 23, so that a portion of this product may be reformed ifdesir-. able.

A conduit 28 having a control valve 29 connects the bottom offractionator l9 with the return line 23, and a pipe 30, controlled by avalve 3|, is also furnished whereby reflux condensate can be withdrawnfrom the system. Instead of the vapors from the flash chamber passingthrough line 18 to fractionator I9 they may be diverted throughcondenser 32 into line 23 by opening valve 33 in line 34 and closingvalve 35 in the line leading to the fractionator.

Fresh charging stock, such as crude oil having a gasoline content, issupplied to the system by pump 31 which forces the oil through a conduit36, cooling coil 38 in fractionator l9, cooling coil 39 in fractionator8, heating coil 40 in the furnace 4, heat exchanger 6 and line 4| whichconnects with the conduit l4 leadingto the flash chamber or still I3.The heat exchangers 38 and 39 and heating coil 40 may be partially orcompletely by-passed as desired by proper manipulation of valves 42, 43,44, 45, B0 and 46. A conduit 41 is also provided for by-passing heatedproducts from coil 3 to fractionator 8 and the amount of fluid by-passedmay be regulated by valves 48 and 49.

The temperature and pressure maintained in heating coil 3 should be thatbest adapted for reforming, or improving the anti-knock rating of thegasoline passing therethrough. The temperature may be for example 900 F.to 1200 F. and. the pressure of any suitable value, for example severalhundred pounds per square inch, although pressure of 1000 to 2000 poundsper square inch may be used. In passing through the heat exchanger 0 thehot products from coil 3 are-reduced in temperature to a lower value, e.g. 500 F. The reducing valve 1 may lower the pressure on the products toapproximately an atmospheric value or this valve may be adjusted topermit approximately the same pressure to obtain in both thefractionator 8 and heating coil 3. The temperature of the combinedproducts in line H! may be 350 F. and the pressure may be of any valuebest suited for a stripping operation. This pressure will usually below, for example 10 pounds per square inch although somewhat higherpressure may be maintained advantageously to prevent vaporization of thecrude oil in the heat exchanger 0. Where low pressure is used nopressure reducing action is needed at valve I6. and on the other hand ifthe higher pressure is used reduction may take place at this valve. Thebottoms may be drawn off from the separator l3 through line 58controlled by valve 5| and be conductedwhile in a heated condition tosome other well known form of cracking system, (not shown) or the oilmay be cooled and put in storage.

The separator l3 may be so arranged and the temperature and pressure ofthe products be so correlated that substantially only gasoline ofsuitable boiling range for motor fuel will be re-, moved therefromthrough the vapor line I8. The gasoline removed may be passed entirelyinto the line 23 leading to heating coil 3 by closing valve 35 andopening valve 33. In this case all of the gasoline products will besubjected to the reformation process. It may be found in certain casesthat only the higher boiling point ends of the gasoline-like productsneed be reformed, the lighter products having a. sufliciently highantiknock rating without such treatment. case liquid products may be;removed from. the fractionator l3 either in the form of refluxcondensate through conduit 28 or as a side stream through the pipe line23, or both. The final products contained in receiving drums ll and I2may be blended if desired by opening valve 52, in line 53 and either ofthe final products or a blend of the two, may be returned to the coil 3through lines 26.. and 23 by proper manipulation of valves 52, 54 and2.1. T'ifty-five (55) and 56' are valved draw-off lines for distillatefrom the receivers H" and 22 respectively, while valved lines 5! and 58serve as gas vents for these chambers.. The reflux condensatenotrecycled from the bottom of fractionator l9 may be withdrawn fronrthe.system through the. conduit 30. ,A corresponding valved line69 providesa means for withdrawing excess condensate from fractionator a. w 7

operation gasoline tolloe reformed to improve its; antirknock valueis-vintroduced through the line I- to heating coil 3 under a temperatureof. any suitable value determined by the characteristicsof the'gasoline,for example 900 F. to 12005 F. and a pressure of; several hundred poundsper; square inch.- The heated products pass through heat exchanger 6 andare somewhat cooled thereby, their exit temperature-being possibly 500F. The partially cooled products are then passed through the pressurereducing valve 1 and expanded into fractionator 8 with the result thatfinal end point vapors pass off through theline 9 and are converted toliquid in thecondenser Il.-,. the, liquid being collected: inaccumulator drum IL, Fractionation in the column 8 is aided by theaction of cooling coil '39 which serves also to heat crude oil or othergasoline containing stock introduced through line 36, as explainedhereinafter. The reflux condensate from fractionator 8 is conducted;through lines l2 and I4 intothe flash chamber or separator l3 along withthe heated crude oil. The vapors from the flash chamber are transferredeither to the condenser 32 or fractionator l9 while the liquid productsfrom the flash chamber are withdrawn through draw-off line 58. If thevapors are conducted to the condenser 32 they are forced by the pump 24to the heating coil 3 along with the natural gasoline, but if they areinstead directed to the fractionator 13 they are. separated into lightervaporous products and liquid. products. The light vaporous products passoverhead,. are partially In this condensed by the action of coil 38 andthose remaining are carried off to the condenser 2| and receiving drum22. Liquid products of the desired boiling point are Withdrawn from thefractionator either through conduit 28 or pipe 23 or both and withoutfurther cooling are introduced into the heating coil 3 by action of pump24. The products returned to the heating coil by the pump just mentionedshould be of a character such that an increase of anti-knock value byreformation is desired and the arrangement of piping which has just beendescribed is provided so that a proper selection may be made. It hasbeen pointed out hereinbefore that the point of removal of the liquidsto be returned to the heating coil will depend upon the character of theproducts being treated as well as the temperature and pressure of theoil in line l4 and the operating characteristics of the flash chamberl3.

The lighter products of certain natural orstraight-run gasolinessometimes also need. reformation tOi increase their anti-knock value andin this case the finaldistillate collected in accumulator drums Harrd'2-2 may be returnedindividually or togetherwith any ofthe liquidproductswhich have already been mentioned as subject. to reformation;According to one desirablermode of operation only gasoline stripped fromthe crude charged to the system is. passed through heating coil 3, forreformation, the supply-of natural gasoline introduced into pipe l being.cut ofi.

Economical operation of thesystem is insured by introducing fresh crudeoil or other oil containing a. certain amount, of gasoline from line 36through pump 31, heat exchanger 38 and 39, heating coil 40 and heatexchanger 6 into. the line l4, leading to the flash chamber 13. By thisarrangement a large amount of the heat neces'- sary to strip thegasoline content, from the crude oil is derived by indirect contactinheat exchanger B, with the vaporous'prod-ucts from heating coil 3 andlikewise by the added heat directly derived from the hot refluxcondensate contributed by fractionator 8. Any added amount of .heatnecessary or desirable for the stripping operation may bederived fromthe heating coil 40' of. the-furnace 4, the amount of heat picked upthis manner being regulated by the proper setting of valves 48 and 8G. 1A. certain amount of heat. is also: picked up by the crude oil inpassing through; vapor cooling col-ls 38. and 39 of the fractionatingcolumns.

I have. described a particular embodiment of my invention for thepurpose. of illustration but it should be understood that variousmodificationsv and adaptations thereof may be made within the scope: ofthe invention, as; set forth by thegfollowing; claims. 1

I; claim:

1. The method of producing gasoline of high anti-knock value whichcomprises stripping crude hydrocarbon oil ina stripping zone to producestraight-run gasoline, separating said gasoline into a lighter portionand a heavier portion, cracking said heavier-portion at high temperatureunder superatmospheric pressure to increase its anti-knock value,passing the resulting cracked products, prior to reduction of thepressure thereon, in indirect heat exchange relationship with the crudeoil to be stripped, subsequently; flashing said cracked products in. azone separate; from said stripping zone to form vaporous gasolineproducts and heavier liquidproducts, combining said liquid products withsaid crude oil after the preheating thereof by said indirect heatexchange step and introducing the resulting mixture into said strippingzone wherein said stripping action takes place.

2. The method of treating hydrocarbon oil which comprises passingrelatively low antiknock naphtha through a heating zone wherein it israised to a reforming temperature and subjected to conversion intohigher anti-knock gasoline constituents, passing the resulting reformedproducts in indirect heat exchange relation with fresh relatively heavycharging stock comprising lighter constituents in the gasoline boilingrange and heavier constituents which has previously been passed throughan externally-fired preheating zone, subsequently introducing saidreformed products into a first zone wherein vapors separate from liquidresidue, fractionating resulting vapors and condensing the fractionatedvapors to form a light distillate, passing the preheated fresh chargingstock from said indirect heat exchange step into a second zone whereinvapors separate from liquid residue, combining said liquid residuefirst-mentioned with said fresh charging stock after the passage thereofin indirect heat exchange with said reformed products to aid in theseparation of vapors therefrom, fractionating said vapors last-mentionedto form a light distillate and blending said light distillates to form afinal desired product.

LE ROY G. STORY.

